Determination of organic sulphides by enthalpimetry using chromyl chloride

Abstract

Thermometric titration with chromyl chloride and direct injection enthalpimetry with the same reagent have been used for the determination of sulphides in hydrocarbon solvents; the second procedure was found to be superior. Chromyl chloride and sulphides react in a 1 : 1 ratio, producing a brown precipitate, the heat of reaction being 250 kJ mol^–1. The limit of determination is 3 p.p.m. and the relative standard deviation 3.3% at 60 p.p.m. of sulphide-sulphur. The method can be applied in the presence of unsaturated compounds and polycyclic aromatic hydrocarbons. Polycyclic aromatic hydrocarbons also react with chromyl chloride, but the reaction with sulphides is dominant. The method has been suggested for the determination of sulphide-sulphur in petroleum products.